1. Field of the Invention
This invention relates to the field of animation projection systems.
2. Background Art
In entertainment applications, a set is often created to provide an artificial environment. These entertainment applications may include, for example, live stage presentations, theme park rides, and museum exhibits. These entertainment applications often use special effects to add to the perceived reality of the artificial environment. Special effects often include elements of lighting, sound, scenery, and/or visual cues to artificially create the visual and environmental impression of natural phenomena, such as fire, rain, clouds, snow, wind, sunlight, etc, or of imaginary phenomena, such as unpowered human flight, mythical creatures, animated cartoon characters, and other fanciful things.
Prior art apparatus used to create visual effects have included the use of projectors to project an image that is combined with physical scenery to provide a desired "combination" image. One such projector is known as a "sciopticon". An example of a sciopticon is illustrated in FIG. 1. The sciopticon includes a light source, such as lamp 100, for projecting light through condensing lenses 101 and 102. The light output of the condensing lenses 101 and 102 is projected through a slide 103. The slide 103 may be a rotatable disk that includes a transparent painted effect, such as, for example, "rippling water", clouds, rain, snow, or moonlight. The output of the slide 103 is projected through an objective lens assembly (objective lenses 104 and 105) to produce an image 106. The image 106 is projected onto a screen 107 or other flat surface.
In some circumstances, it is desired to simply project the outline or shadow of a moving character onto a surface or scene. A prior art technique to accomplish this utilizes a mechanical model of a character, referred to as a "maquette". The maquette is placed between a light source and a surface so that the shadow of the maquette is projected onto the surface. Such a scheme is illustrated in FIG. 2A. In FIG. 2A, the light source 200 is disposed some distance away from a projection surface 202. A maquette 201 is placed between the light source 200 and the surface 202. The maquette 201 may be mounted on a track 203 via mounting post 210. Motive force is applied to the maquette so that its shadow appears to move across the projection surface. Often, the maquette 201 is mounted on a circular or looped track so that it rotates through the light beam during one portion of a revolution and is hidden from sight during the remaining portion of the revolution. A disadvantage of the use of a maquette is that the shadow 210' of the mounting post 210 is also projected onto the projection surface. This detracts from the realism of the environment.
Referring now to FIG. 2B, the maquette 201 is shown mounted on a loop track 204. The track 204 itself is disposed in a housing 205 so that it does not cast a shadow onto the projection surface 202. As the track is turned, the maquette 201 is in a path between the projector 200 and the projection surface 202 in the approximate upper half of the loop defined by the track 204, from positions 207 to 208. During this time, the shadow 201' of the maquette 201 is projected onto surface 202 and appears to "move" across the surface 202 as the track turns. At position 208, the maquette is rotated below the level of the housing 205 so that no shadow of the maquette is projected. The track continues to turn and the maquette returns to position 207 and the cycle of shadow projection and shadow masking is repeated. The scheme of FIG. 2B also has the disadvantage of the projection of the shadow 210' of the mounting post 210.
Instead of a maquette, a shadow mask, (referred to as a "gobo"), may be installed at the focal plane of the projector, thereby casting a silhouette on the projection surface. However, such a scheme is not suitable for animated characters or imagery.
The prior art projection schemes described above both have the disadvantage of requiring a substantially fiat projection surface for suitable operation and to accomplish their desired visual effects. This requires the inclusion of a fiat planar surface in the midst of a three dimensional scene or set. The presence of such a fiat planar surface is typically obvious and visually "jarring" to the observer. It provides an undesirable reminder that the environment is artificial, and disrupts the desired continuity and visual integration of the effect. This is a particular problem in the theme park attraction and "dark ride" industry. A dark ride is a ride that includes transportation of a rider or riders through a light controlled region. The interior region may be intended to represent a tunnel, the inside of a mountain, a house, or an outdoor scene.
The intention of many theme park attractions is to give the impression that the rider is being transported through a fully dimensioned and visually uniform and integrated fantasy world. Fully dimensioned means the use of three dimensional sets and set pieces, the use of textured surfaces, color, sound, and lighting to give the illusion of reality. Often the interiors of these environments is comprised of three dimensional sculpted forms made from plaster, foam, and concrete. These forms are often referred to as "rock-work". The inclusion of a relatively fiat projection surface with the three dimensional surfaces of the rock-work detracts from the overall impression of the space and becomes an obvious, artificial object itself.
Another disadvantage of the prior art projection schemes and apparatus described above is the time intensive nature of the set-up required for these systems, and the requirement for having fixed preinstallation dimensions,objects, angles, textures, and placements of the systems in the entertainment environments. This is often at odds with the construction of theme park attractions. These visual effects are typically the last component to be installed in an attraction, often just days prior to opening of the attraction. The nature of construction of rock-work, the last minute changes of designs, the placement of other support systems for the attractions, (air conditioning, electrical cabling, lighting, etc.), can result in a constructed environment very different from the designed environment. In addition, the originally selected location may not provide the desired effect, necessitating the relocation of the projection system or the destruction and rebuilding of portions of the set.
The destruction and reconstruction of a set, particularly when rockwork is involved, is costly and time consuming. In a theme park attraction, the rock-work alone can cost in the millions of dollars. Therefore, it is desirable to avoid modifying a set once it has been constructed. However, with prior art projection schemes, set reconstruction is often the only alternative.
The perspective and location of a projected image is dependent on the shape, angle, and location of the projection surface, the location and angle of the projector, and the size of the maquette or slide images. Because each of these variables may be changing until days or hours before the attraction is to begin operation, it is difficult if not impossible to complete and implement the projection system in advance of the installation of the attraction. In practice, a system of trial and error is utilized after the set is completed and the projector is installed in order to obtain desired registration of the projected image with the projection surface. The slide images and/or maquette may need to be modified or redone to provide proper scaling and perspective.
Another difficulty with the prior art schemes is the requirement of a projection surface that is designed into the set. It may be desired to provide a projected effect on an existing region of a three dimensional environment, even if that region was not originally designed as a projection surface. This is not practical with existing prior art projection schemes.
There have been prior art attempts to eliminate the need for a relatively flat projection surface by projecting still images or animated images directly onto the three dimensional surfaces. Attempts to project animated images onto three dimensional surfaces are limited to simple effects, such as water ripple, but have been found impractical due to overly complex and/or expensive equipment for more complex image projection.
To project a still image onto a three dimensional surface, the prior art uses a technique whereby a photograph of the projection surface is produced. This photograph is produced using the same objective and condensing optics that will eventually be used for the projection itself. The photograph would include all the perspective and lens-induced distortions of the interaction of the projection system and of the projection surface. A designer then uses this photograph to produce a still image that "registers" with the projection surface. The distortions and perspective characteristics are designed into the still image. When the still image is projected onto the projection surface, the distortions and perspective characteristics are compensated out by the design.
A disadvantage of this scheme is the fact that it is limited to still images. In addition, the process is painstakingly iterative. The designer must periodically project the work in progress onto the projection surface to determine the success of the design registration. This iterative process is time consuming, and impractical for applications where the environment is either evolving, or where there may be a desire to have the effect be transportable to a modified scene or background.